Land Rover Oem Hitachi Air Compressor Fault Diagnosis 

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Hi Alan, You can,t really determine correct pressure output with the test you mention,in our experience changing all the components that are connected with outgoing pressure if you are not certain what components are failing is the only way, delivery valve ,piston seals ,air dryer filtration with end cap ,clean out electric motor & exhaust electrical solenoid making them free from dust ,check that the electric motor windings are not totally discoloured due to over heating this can reduce the electric motor performance,get your diagnostic codes read to see if the current vehicle fault is connected with the compressor performance. thanks

Hi Alan, Testing the outgoing air pressure on the bench by placing your finger over the port is not any real indication to the correct outgoing pressure ! if u repeated the same test with a new pump it would be very similar to the one with your original pump ! the only way on the bench to test the pressure is ! if you can get hold of a brand new pump the same as the one you are testing and rig up a test guage that can pass air thru it and give a reading ,u would need to test with a fully charged battery the new pump and write down the reading and then get your old pump and compare the 2 otherwise the compressor as to be tested in situ on the vehicle using live data diagnostic testing. thanks

Yes putting thumb over port isnt a great test of knowing the output pressur the only way is with diagnostic live data as compressor is running on vehicle !16.8 bar is the system pressure that the compressor fill the resorvoir tank to ,check when compressor stops that the air pressure in the gallery isnt leaking away .

Hi, Unfortunately we have noticed that the aluminium covers which are sold by other sellers have been prone to leaks at the operating pressure 16.8 bar ,our own in house manufactured covers are manufactured and assembled at the operating pressure of the vehicle without leakage ,if u artificially put into 15.8 bar to 16.8 bar of air pressure into the air dryer of the compressor then spray leak detector around the fittings on the end cap this will test if the cap is causing the fault ,if u require a replacement cap after your tests please visit our website www.4x4airseals.com

Not normally ,we suspect their is a air leak somewhere causing the vehicle to dip on a corner then the rest of the vehicle is adjusting to that level to try and level the car up ,with regards to your compressor ,when you start your vehicle the cars system does a plausibilty check if it thinks their is a fault anywhere and its not a severe fault then the system will try to get the vehicle height to normal ride height then usually display a message ' normal ride height only ' on the dashboard and switch the compressor off ,we advise to get your vehicle diagnostic codes read to see what particular system is failing ,please get back to us with the codes if possible. thank's

The vehicle does a quick test itself every time you switch on the vehicle and if it as a mild fault it will always try and get the vehicle to normal rideout b4 illuminating any dashboard messages ,if the vehicle sinks down overnight it must be loosing air and which ever corner/corners are leaking will usually level up to the leaking corner or height sensor / sensors are giving a rogue reading. thank you

Sounds like you have an air leak somwhere on the vehicle ! air pipe on top of back axle is notorious for leaking , try leak detector over all air lines and pressure switch valve solenoid next to compressor ! valve block solenoids 3off total could do with fitting with new orings which we can supply from our web store or ebay store if required.

hi, We Would Need to know which type of compressor u have fitted !1 of 3 types oem hitachi aftermarket dunlop or amk ,we can supply kits for all 3 ,u can send whatsapp picture of your unit if req 07908 479400 f u get your diagnostic codes read that would be good so we know what system the vehicle isnt happy with ,thank you

Hi again it was a aftermarket on claiming to be hitachi .. which had been thrown in the trash .. I’ve now got a replacement genuine one

I,m Sorry the trouble code B1D60-64 is a code we have no knowledge or experience with.

Its quite common for some garages to jack up the vehicle in the wrong place especially under the rear passenger floor were the compressor box compartment is , its adviseable to get the car over a ramp and inspect the complete under side incl the receiver tank under the drivers floor .

@@4x4airsealstechnical99 I just inspected the air compressor with it still mounted. From what I can see and based off of it raising and lowering just fine, the air compressor appears to be fine but the mounting arm is totally shattered from the full weight of the vehicle being on it. Is that part still available on your website or do you know where I can get one for the best price? Thank you for your help!

Hi, The usual cause of compressor failure are air leaks around the vehicles air suspension system which the old compressors seemed to put up more of a fight with stronger more robust electric motors ,but nowadays their appears !only in our opinion, to be a lot of cheaply built compressors flooding the market which seemed to be built not as robust in the electric parts of the compressors,air leaks is still the number one cause of compressor failure in our view,air leaks can be very slight and difficult to trace, theirs usually 1 bar of pressure between the compressor running and switching off so if on range rover sports n disco 3 4 the system pressure gets to 16.8 bar the ecu tells the compressor to switch off but if you have a slight leak in the vehicle and it drops to 15.8 bar it tells compressor to switch on and their is the problem the compressor gets very hot and how long it lasts is anyone's guess ,servicing the compressor air dryer filtration periodically will help the compressor also. thank you

We find a lot of cheap new aftermarket compressors are not quite the same quality as the original oem units especially the electrical side of the compressors , but generally slight air leaks that are hardly noticeable and take some time to diagnose cause the new compressors to over run and thus reduce service life ! getting rid of air leaks and issues causing the compressor to struggle filling tank to 16.8 bar need to be diagnosed and sorted or the cycle of replacing compressor's continue.

c112f - corner valve stuck open or corner valve leak to gallery c1130- air spring leak/ air harness leak/corner valve leak to gallery /exhaust valve stuck open . Not likely to be a compressor fault but u can also check that their is no air coming out of exhaust port on air suspension compressor whilst the compressor is running.

Yes if you have a noisy compressor it could be the piston seal is worn and causing some piston slap ,also if the air intake pipe and exhaust outlet pipes have become detached and the in and outgoing air pressure is not being silenced ,if you have a dashboard message appearing get your diagnostic codes read and write them down and drop us a message,thanks

Yes the 1st thing to do is to have the diagnostic codes read to see which system the vehicle is currently having problems with ,the common fault codes are c1a20 or c1a13 or both but their may be other codes that appear,2nd check to see which type of compressor is fitted to your vehicle hopefully it is the oem hitachi unit . thanks

@@4x4airsealstechnical99 Which scan tool can I purchase to read the diagnostic codes, my Bosch scanner does not as far as I can tell.

Most local garages would read the codes for you for a little cost avoid great expense purchasing a scan tool,just ask them to write down the codes for you then ask them to clear the codes ,we can tell what the common codes mean if you let us know. Thanks

Sorry not got that code in my std land rover error code listing .

Hi, This code is a general compressor fault and is not specific enough in it description,std hitachi oem units and dunlop aftermarket units always usually suffer from leaks after a period of time and replacing the filtration and end cap as a minimum service which can sort these types of codes,if u can fully service your unit with our main kit it can help the whole vehicle suspension system .Thanks

detched air pipe /insufficient pressure from compressor /loose or burst pipe/ resorvoir pipes incorrectly fitted unions reversed/pressure sensor fault.